Hi Tetsuya,

On 1/14/2016 12:27 PM, Tetsuya Mukawa wrote:

On 2016/01/12 15:58, Yuanhan Liu wrote:
Hi Yuanhan and Jianfeng,

Thanks for great patches.
I want to use VIRTIO-1.0 feature for my virtio container patch, because
it will solve 44 bit memory address limitation.
(So far, legacy virtio-net device only receives queue address under (1
<< (32 + 12)).)

I suppose you are specifying the code below:
         /*
          * Virtio PCI device VIRTIO_PCI_QUEUE_PF register is 32bit,
          * and only accepts 32 bit page frame number.
          * Check if the allocated physical memory exceeds 16TB.
          */
         if ((mz->phys_addr + vq->vq_ring_size - 1) >> 
(VIRTIO_PCI_QUEUE_ADDR_SHIFT + 32)) {
                 PMD_INIT_LOG(ERR, "vring address shouldn't be above 
16TB!");
                 rte_free(vq);
                 return -ENOMEM;
         }

So you don't need to add extra cmd option, right?

I have a few comments to rebase virtio container patches on this patches.

1. VIRTIO_READ_REG_X

So far, VIRTIO_READ_REG_1/2/4 are defined in virtio_pci.h.
But these macros are only referred by virtio_pci.c.
How about moving the macros to virtio_pci.c?

+1 for this.

2. Abstraction of read/write accesses.

It may be difficult to cleanly rebase my patches on this patches,
because virtio_read_caps() is not abstracted.
Let me describe it more.
So far, we need to handle below 3 virtio-net devices..
  - physical virtio-net device.
  - virtual virtio-net device in virtio-net PMD. (Jianfeng's patch)
  - virtual virtio-net device in QEMU. (my patch)

Almost all code of the virtio-net PMD can be shared between above
different cases.
Probably big difference is how to access to configuration space.

Yuanhan's patch introduces an abstraction layer to hide configuration
space layout and how to access it.
Is it possible to separate?
I guess "access method" will be nice to be abstracted separately from
"configuration space layout".
Probably access method will be defined by "eth_dev->dev_type" and the
PMD name like "eth_cvio".
And "configuration space layout" will be defined by capability list of
PCI configuration layout.

For example, if access method like below are abstracted separately and
current "virtio_pci.c" is implemented on this abstraction, we can easily
re-use virtio_read_caps().
  - how to read/write virtio configuration space.
  - how to mmap PCI configuration space.
  - how to read/(write) PCI configuration space.

I basically agree with you. We have two dimensions here:

legacy             modern
physical virtio device:                     Use virtio_read_caps_phys() 
to distinguish
virtual virtio device (Tetsuya):       Use virtio_read_caps_virt() to 
distinguish
virtual virtio device (Jianfeng):    does not need a "configuration 
space layout", no need to distinguish

So in vtpci_init(), we needs to test "eth_dev->dev_type" firstly

vtpci_init() {
     if (eth_dev->dev_type == RTE_ETH_DEV_PCI) {
         if (virtio_read_caps_phys()) {
             // modern
         } else {
             // legacy
         }
     } else {
         if (Tetsuya's way) {
             if (virtio_read_caps_virt()) {
                 // modern
             } else {
                 // legacy
             }
         } else {
             // Jianfeng's way
         }
     }
}

And from Yuanhan's angle, I think he does not need to address this 
problem. How do you think?

Thanks,
Jianfeng

Thanks,
Tetsuya